I once paid someone on airtasker to research me ten cafes in Melbourne that have carpet. They only found one, and I already knew it. It has since closed.
Wetherspoons (pub chain in the UK, divisive in that it is a hive of villany while simultaneously being one of the few places you can get a well kept real ale) have individual carpets in each of their venues. This has, as you can imagine, become a hobby.
I'm pretty sure you could measure this with a mobile phone app, if such a thing doesn't already exist. I've already many times used such an app to measure acoustics in a room as part of the setup process for multiple brands of home speaker system, they emitted a range of frequencies and presumably measured the result using the microphone.
Where are you finding these old school restaurants? We need to make lists.